(1) Field of the Invention
A conventional information retrieval apparatus manages user's information, and commonly uses the same user's information for information retrieval from a plurality of data bases (for example, refer to Japanese Laid-Open Patent application No. 07-152771).
Also, another conventional information retrieval apparatus manages, per category, user's information (personal preference information) indicating digitized user's preference. The information retrieval apparatus provides each information transmission source with the user's information associated with the category, the information transmission source having a respective data base. Thus, the information retrieval apparatus causes each information transmission source to execute information retrieval and the like (for example, refer to Japanese Laid-Open Patent application No. 2002-269144).
However, according to the information retrieval apparatus disclosed in the above mentioned Japanese Laid-Open Patent application No. 07-152771, all of the details included in one user's information are used for retrieving a plurality of data bases which have different use frequencies. Thus, there is a problem that information associated with the user's preference cannot be properly retrieved in the case of using a data base which has a low use frequency.
FIG. 1 is an illustration for explaining the problem caused by the information retrieval apparatus disclosed in the above mentioned Japanese Laid-Open Patent application No. H7-152771.
For example, as shown in FIG. 1, in the first data base which has a high use frequency, an Electric Program Guide (EPG) 1 of terrestrial broadcast is stored. In the second data base which has a low use frequency, an EPG 2 of Broadcast Satellite is stored. And, the information retrieval apparatus manages a single user's information 3 indicating the user's preference. In the user's information 3, starting from the user's strongest preference, for example, keywords (Matsuue Electric, economy, Ryudai Mine, sports and entertainment) and the like are sequentially stored.
The information retrieval apparatus uses all of the keywords stored in the user's information 3 in order to retrieve TV programs stored in the EPG 1 that is the first data base and in the EPG 2 that is the second data base.
In other words, from the EPG 1 that is the first data base, TV programs including the most strongly preferred keyword “Matsuue Electric” are retrieved among all genres such as news, entertainment show and variety. Also, from the EPG 2 that is the second data base, TV programs including the most strongly preferred keyword “Matsuue Electric” are retrieved among all genres.
Since the user desires to watch all of the TV programs including the key word “Matsuue Electric”, the user has no complaints about the above mentioned retrieval.
Here, for example, in the terrestrial broadcast Ryudai Mine frequently appears in the genre of entertainment show, and in the Broadcast Satellite Ryudai Mine frequently appears in the genre of shopping. Since the user frequently uses the EPG 1 that is the first data base, the user expects that Ryudai Mine appears not in the genre of shopping, but in the entertainment show. Due to such expectation as described above, the user's preference for the keyword “Ryudai Mine” is not very strong.
However, the information retrieval apparatus uses, for the EPG 1 and the EPG 2, all of the keywords included in the user's information, the information retrieval apparatus being disclosed in the above mentioned Japanese Laid-Open Patent application No. 07-152771. Thus, TV programs including the keyword “Ryudai Mine” in each of the EPG 1 and the EPG 2 are retrieved in all of the genres.
As a result, the TV programs related to shopping which the user does not expect are retrieved from the EPG 2 that is the second data base. Thus, according to the above mentioned information retrieval apparatus, the TV programs associated with the user's preference cannot be properly retrieved.
In addition, for example, among the terrestrial broadcast TV programs including the keyword “entertainment” there are many TV programs which introduce drama actors and the like. Among the Broadcast Satellite TV programs including the keyword “entertainment” there are many TV programs such as kabuki. Since the user frequently uses the EPG 1 of the first data base, the user expects, from the keyword “entertainment”, the TV programs which introduce drama actors and the like.
However, the information retrieval apparatus uses, for the EPG 1 and the EPG 2, all of the keywords included in the user's information, the information retrieval apparatus being disclosed in the above mentioned Japanese Laid-Open Patent application No. 07-152771. Thus, TV programs including the keyword “entertainment” in each of the EPG 1 and the EPG 2 are retrieved in all of the genres.
As a result, the TV programs related to kabuki which the user does not expect are retrieved from the EPG 2 that is the second data base. Thus, according to the above mentioned information retrieval apparatus, the TV programs associated with the user's preference cannot be properly retrieved.
Moreover, the information retrieval apparatus differentiates the user's information per information transmission source (per data base), the information retrieval apparatus being disclosed in the Japanese Laid-Open Patent application No. 2002-269144. However, the information retrieval apparatus cannot provide the information transmission source with the proper user's information, the information transmission source having a low user's use frequency. Thus, there is a problem that the information associated with the user's preference cannot be properly retrieved.
(2) Description of the Related Art